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Do you want to install solar panels in your home? There are a lot of solar installer services available, but it helps to know something about how the system works. For instance, which is better, solar panels or inverters?
These are two different devices that complement each other. Solar panels convert sunlight into direct current (DC). An inverter turns DC into alternating current (AC) so appliances can run.
What are Solar Panels?
Solar panels are devices that transform energy from the sun and turn it into direct current (DC) electricity. They are also called PV (photovoltaic) solar panels.
Solar panels are built out of crystalline silicon . All panels are either black or blue because that is the color silicon produces when it is made.
Size. Solar panels are comprised of individual square called cells. A 60 cell solar panel is 3.25 x 5.5 feet (39 x 65 inches), while a 72 cell
panel measures 3.25 x 6.42 feet (39 x 77 inches).
Longevity. The average solar panel has a 25 year warranty. If your solar panel has a 25 year warranty, it is guaranteed to produce at least 80% of its capacity for the next 25 years.
Some manufacturers now offer even longer warranties. Others like the Renogy 2 pcs solar panel kit last even longer because they are of higher quality.
Solar Panel Efficiency Explained
This is one of the most misunderstood aspects of solar power. A lot of solar panels have a 20-25% efficiency rating, which some misconstrued to mean it only runs at 20-25% of its rated capacity.
That is not true.
Solar panel efficiency refers to how much of the sun’s energy is being turned into electricity. Most solar panels for home have a 22% efficiency rating, with 25% becoming more common.
This has nothing to do with a solar panel’s output.
A 300W solar panel with a 22% efficiency rating converts 22% of the sun’s rays into electricity. This has nothing to do with its rated watt output.
A 300W solar panel can produce a maximum of 300 watts an hour. Realistically though, it will only reach its maximum watt output at certain times of the day like high noon.
Cloud covers, shade and anything that comes between the sun and the solar panel will reduce its output. In ideal conditions, a 300W solar panel can produce 280W-290W an hour, peaking at 300W at certain times.
So how does efficiency affect the rated output? The higher the efficiency rating, the more sunlight a solar panel can convert. If 25% of the light is converted into solar power, that means a higher output.
Grid Tied vs. Off Grid Solar Panels
Solar panels only produce energy when the sun is out. To keep the lights on at night, you have to store solar energy somewhere. There are three options: a grid tied system, off the grid and grid tied with battery.
Grid tied: your solar panel system is connected or tied to the utility grid. The solar power you produce is transmitted into the grid and used to service other homes.
In exchange you get credit from the grid which allows you to use energy at night. If your home is tied to the grid you can switch back and forth between solar and grid anytime.
Off the grid: without access to the grid, you will need a battery bank to store solar energy. Batteries like the LiTime lithium battery are essential if you live in a remote area without power lines or just want to be grid independent.
You can also install battery banks in a grid tied solar panel system. It is an extra cost, but a good investment if your area is vulnerable to harsh weather and blackouts.
Grid tied with battery. For safety reasons, grid tied solar panels cannot run during a power outage. With a battery bank, you have backup power available. If your system has a solar battery, it also has charge controllers.
What is a Solar Inverter and How Does it Work?
A solar inverter is the device that makes it possible to run appliances on solar power. There are different types of inverters but the power conversion process is similar.
When sunlight hits the solar panel, it is turned into direct current (DC). In a grid tied solar system, DC is transmitted into the inverter where it is changed into AC.
The primary role of an inverter is to make certain the power produced by solar panels will work with the grid. By turning DC to AC, compatibility problems are avoided.
Inverters have other functions.
- Solar panel and grid synchronization
- Provides information on solar power production
- Tracks your solar energy usage
Some solar inverters can disconnect your solar panels from the grid in case of an outage. If you have a battery bank, you can use that as backup power.
Types of Inverters
There are two kinds of inverters: microinverters and string inverters. They both turn DC to AC but there properties are very different.
String inverters transform DC to AC for a string of solar panels (hence the name). These are the cheapest type and remain quite popular.
Another benefit of string inverters is they can be installed in convenient locations. So in case it needs servicing, the device is within easy reach.
The biggest disadvantage of string inverters is the way it handles solar power production. If one of the solar panels gets shaded and reduces output, the rest of the panels are affected.
String inverters are a good option if there is no shading on your roof the entire day. Otherwise you should consider microinverters instead.
You can also use power optimizers with a string inverter. The inverter still performs the current conversion, but a power optimizer allows each solar panel to generate current independently. So if one panel is obstructed, the others will not be affected.
Microinverters also convert DC to AC, but for each solar panel. There is a microinverter for each panel so if one is obstructed, the others are not affected.
Microinverters cost more than string inverters but are more efficient. If part of your roof gets shaded, you will get better results with microinverters.
Aside from the cost, one disadvantage of microinverters is higher servicing fees. Because the inverters are linked to the solar panels, the technician has to get on the roof to fix it.
However, microinverters have 25 year warranties compared to 10-12 years for string inverters. If a problem does occur the warranty should cover it. My personal choice is the CNCEST microinverter because it is efficient and built to last.
Solar Inverter Efficiency Explained
During the DC to AC conversion, some energy will be lost. This is normal as no solar inverter is 100% efficient.
The best inverters have a 90-95% efficiency rating. The higher the rating, the more electricity can be converted and used.
There used to be a time when 85% efficiency was considered high end. But solar inverters have improved and there are higher quality products now available.
How Solar Panels and Inverters Work Together
Solar panels and inverters cannot be compared because they have different functions. Both are required if you want to use solar energy to power your home or RV.
Solar panels can convert sunlight into electricity but as direct current (DC). You can run DC compatible devices directly from solar panels, but not those that run on alternating current (AC).
Majority of appliances and electronics require AC, so solar panel systems have inverters. Whether they are microinverters or string inverters, both do the same thing: turn DC into AC.
What Inverter Do I Need For My Solar Panels?
The most important factors to consider are the inverter type and capacity.
The inverter capacity has to match that of the solar panel. You need the inverter to run all your appliances off solar, so the capacity has to match the demand.
The easiest way to figure this out is to look at your monthly power bill. The monthly kilowatt (kwh) usage tells you how much solar panel and inverter capacity you will need.
Decide if you are going to install a battery bank. This is not needed if you are on the grid, but if you want backup power available it is an option.
Buying solar batteries is an added expense. But if you want backup emergency power, it is a good choice. You cannot use grid tied solar panels during a power outage, so if you want to keep the lights on, batteries could be the answer.
I am an advocate of solar power. Through portablesolarexpert.com I want to share with all of you what I have learned and cotinue to learn about renewable energy.